Composition for flexible device substrate formation

Abstract

This invention provides a composition for forming a flexible device substrate, which is transparent even without fluorine atoms, has high heat resistance, and can form a resin film with good adhesion to an inorganic insulating film when forming electrodes on polyimide. A composition for forming a flexible device substrate contains component (A), and at least one of component (B) and component (C). Component (A): A polyimide precursor having a structure derived from a tetracarboxylic dianhydride or a derivative thereof having the structure shown in formula (O-t) or (O-d) and a diamine having the structure shown in formula (O-d), and also having one or both of the structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying condition (i) and a diamine satisfying condition (ii), and is free of fluorine atoms; component (B): An imidization accelerator; component (C): A silane coupling agent. (Conditions (i) and (ii) are as described in the specification).

Description

Technical Field

[0001] This invention relates to a polyimide precursor resin composition capable of producing a polyimide film with excellent transparency, low coefficient of linear thermal expansion, high heat resistance, and excellent adhesion to inorganic insulating films. Furthermore, this invention relates to polyimides, polyimide films, and substrates exhibiting excellent transparency, low coefficient of linear thermal expansion, high heat resistance, and excellent adhesion to inorganic insulating films. Background Technology

[0002] In recent years, with the development of thin-film display devices such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs), there has been a demand for thinner, lighter, and more flexible devices. These display devices use glass substrates, but by replacing the glass material with a soft and lightweight resin material, thinner, lighter, and more flexible devices can be achieved. Against this backdrop, polyimide, as a glass alternative, has attracted attention and is being actively researched. In particular, OLEDs have a structure that stacks thin films such as hole injection layers and light-emitting layers on electrodes, making them easily flexible; therefore, the development of flexible OLEDs using polyimide films is underway. In these display devices, various electronic components, such as inorganic insulating films, thin-film transistors, and transparent electrodes, need to be formed on the substrate. Therefore, the material used for the substrate needs to have high heat resistance, such as above 400°C, to withstand the processing temperatures used to form these electronic components. Consequently, for polyimide used in this application, not only heat resistance and flexibility are required, but in most cases, the same transparency as glass is also required.

[0003] Aromatic fluorinated polyimides are widely used as materials with high flexibility, excellent heat resistance and transparency. However, in recent years, due to environmental concerns about fluorine atoms, there has been a growing trend to curb their use.

[0004] Methods have also been proposed to achieve transparency by imparting flexibility to the polyimide backbone and introducing large side chain groups, thereby hindering the formation of intramolecular conjugated and charge-transfer complexes. For example, Patent Document 1 discloses an aromatic polyimide with a flexible polymer backbone, and Patent Document 2 discloses a polyimide with large side chain groups. These polyimides have excellent transparency; however, they sometimes have poor heat resistance, and sometimes their flexibility is reduced due to the large side chains, making it difficult to exhibit the bendability required for flexible displays. When using polyimide as a substrate, a method called laser peeling, in which the polyimide is peeled off from the support substrate by irradiating a laser from the support substrate side after fabricating electronic components on the polyimide formed on the support substrate (Patent Document 3), has been studied. In this case, if the flexibility of the polyimide film is insufficient, there are problems such as damage to the display element during peeling and breakage of the display element during repeated rolling and unrolling. In contrast, as a method that balances excellent flexibility and processing cost, a substrate on which a polyimide film is formed on a thin glass substrate has also been proposed (Patent Document 4). This document discloses a method using 70... m Tens of m-sized glass surfaces formed m The polyimide film of m does not require the use of expensive laser stripping methods to remove the polyimide film, and can be used to manufacture display elements with excellent flexibility.

[0005] However, depending on the application, when forming electrodes on polyimide, the inorganic insulating film has poor adhesion to the polyimide, and sometimes the inorganic insulating film peels off from the polyimide during the high-temperature processing during electrode formation.

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2012-146905 Patent Document 2: Japanese Patent Application Publication No. 2005-306983 Patent Document 3: Japanese Patent Publication No. 2007-512568 Patent Document 4: Japanese Patent Application Publication No. 2021-26232 Summary of the Invention

[0007] The technical problem that the invention aims to solve The purpose of this invention is to provide a composition for forming a flexible device substrate, which is transparent even without fluorine atoms, has high heat resistance, and can form a resin film with good adhesion to an inorganic insulating film when forming electrodes on polyimide.

[0008] Technical solutions for solving technical problems In order to solve the above-mentioned problems, the inventors conducted repeated and in-depth research and found that a composition containing a specific polymer and a specific additive can solve the above-mentioned problems, thereby completing the present invention.

[0009] Therefore, the present invention provides the following composition for forming a flexible device substrate and a flexible device substrate.

[0010] [1] A composition for forming a flexible device substrate, comprising component (A), and at least one of component (B) and component (C); (A) Composition: Polyimide precursor having: a structure derived from a tetracarboxylic dianhydride or a derivative thereof having the structure shown in formula (0-t) or (0-d) and a diamine having the structure shown in formula (0-d), and also having one or both of a structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying condition (i) and a structure derived from a diamine satisfying condition (ii), and having no fluorine atom; Condition (i): When there are two dicarboxylic anhydride sites in the molecule that are directly bonded to the aromatic rings, and there are multiple aromatic rings bonded to the dicarboxylic anhydride sites, the aromatic rings bonded to the dicarboxylic anhydride sites are bonded to each other by single bonds, or via aromatic rings, or fused together. Condition (ii): When there are two amino groups directly bonded to the aromatic rings in the molecule, and multiple aromatic rings bonded to the amino groups are present, the aromatic rings bonded to the amino groups are bonded to each other by single bonds, or via aromatic ring bonds, or fused together. [Chemistry 1]

[0011] (In the formula, the hydrogen atom on the benzene ring can be replaced by a group selected from halogen atoms, alkyl groups with 1 to 3 carbon atoms, alkoxy groups with 1 to 3 carbon atoms, and phenyl groups that can have substituents. The two benzene rings bonded to the fluorene at position 9 can be bonded to each other by single bonds or ether bonds. The benzene rings in the fluorene skeleton can be replaced by naphthalene rings. The dashed line in formula (0-t) represents the bond with the anhydride site, and the dashed line in formula (0-d) represents the bond with the group having the anhydride site in tetracarboxylic dianhydride, and the bond with the group having the amino group in diamine.) (B) Ingredient: Imidization accelerator; (C) Component: Silane coupling agent.

[0012] Invention Effects By using the flexible device substrate forming composition of the present invention, resin films with excellent adhesion to the substrate and inorganic insulating film, transparency, and heat resistance can be reproducibly obtained. In particular, the aforementioned adhesion and transparency can be well maintained even after heat treatment in the TFT process, thus preventing damage to circuits during the manufacturing process of flexible electronic devices and functioning as a permanent film for maintaining transparency after the manufacturing process. Therefore, the flexible device substrate forming composition of the present invention can contribute to simplifying the manufacturing process of flexible electronic devices and improving their yield. Detailed Implementation

[0013] The present invention will now be described in more detail.

[0014] The flexible device substrate forming composition of the present invention contains component (A), and contains at least one of component (B) and component (C).

[0015] (A) Composition: Polyimide precursor having: a structure derived from a tetracarboxylic dianhydride or a derivative thereof having the structure shown in formula (0-t) or (0-d) and a diamine having the structure shown in formula (0-d), and also having one or both of a structure derived from a tetracarboxylic dianhydride or a derivative thereof satisfying condition (i) and a structure derived from a diamine satisfying condition (ii), and having no fluorine atom; Condition (i): When there are two dicarboxylic anhydride sites in the molecule that are directly bonded to the aromatic rings, and there are multiple aromatic rings bonded to the dicarboxylic anhydride sites, the aromatic rings bonded to the dicarboxylic anhydride sites are bonded to each other by single bonds, or via aromatic ring bonds, or fused together.

[0016] Condition (ii): When there are two amino groups directly bonded to the aromatic rings in the molecule, and multiple aromatic rings bonded to the amino groups are present, the aromatic rings bonded to the amino groups are bonded to each other by single bonds, or via aromatic ring bonds, or fused together.

[0017] [Chemistry 2]

[0018] (In the formula, the hydrogen atom on the benzene ring can be replaced by a group selected from halogen atoms, alkyl groups with 1 to 3 carbon atoms, alkoxy groups with 1 to 3 carbon atoms, and phenyl groups that can have substituents. The two benzene rings bonded to the fluorene at position 9 can be bonded to each other by single bonds or ether bonds. The benzene rings in the fluorene skeleton can be replaced by naphthalene rings. The dashed line in formula (0-t) represents the bond with the anhydride site, and the dashed line in formula (0-d) represents the bond with the group having the anhydride site in tetracarboxylic dianhydride, and the bond with the group having the amino group in diamine.) (B) Ingredient: Imidization accelerator; (C) Component: Silane coupling agent.

[0019] The following is a detailed explanation of each component.

[0020] [(A) Polyimide precursor] The polyimide precursor of component (A) is the following polyimide precursor: having a structure derived from tetracarboxylic dianhydride (also referred to as tetracarboxylic dianhydride (t0) in this invention) having the structure shown in formula (0-t) or (0-d) above, and a diamine (also referred to as diamine (d0) in this invention) having the structure shown in formula (0-d) above, and also having one or both of the structures derived from tetracarboxylic dianhydride (also referred to as tetracarboxylic dianhydride (t1) in this invention) satisfying condition (i) above and a diamine (also referred to as diamine (d1) in this invention) satisfying condition (ii) above, and not containing fluorine atoms.

[0021] Examples of tetracarboxylic acid derivatives include tetracarboxylic acid dianhydrides, tetracarboxylic acids, tetracarboxylic acid dihalides, tetracarboxylic acid dialkyl esters, or tetracarboxylic acid dialkyl ester dihalides.

[0022] Examples of substituents for phenyl groups that can have substituents in formulas (0-t) and (0-d) include: halogen atoms other than fluorine atoms, alkyl groups having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, cyano groups, etc.

[0023] As tetracarboxylic dianhydrides (t0), the compounds represented by the following formulas (t0-1) to (t0-5) can be listed.

[0024] [Chemistry 3]

[0025] The preferred diamine (d0) is a compound represented by the following formula (0-d-1).

[0026] [Chemistry 4]

[0027] In equation (0-d-1), P 1 and P 2 Each can independently represent a single bond, -O-, -S-, -CO-, and -NR. 7 -、-CO-NR 7 -、-NR 7 -CO- or -NR 7 -CO-NR 7 -. R 7This refers to a monovalent hydrocarbon group containing 1 to 10 carbon atoms, where one or more hydrogen atoms in the hydrocarbon group are replaced by a halogen atom other than a fluorine atom or a cyano group, or a monovalent thermally leaving group. As a monovalent thermally leaving group, any group that is replaced by a hydrogen atom through heating is acceptable; tert-butoxycarbonyl, 9-fluorenylmethoxycarbonyl, etc., are preferred.

[0028] Q 1 And Q 2 Each of these groups independently represents a divalent aromatic hydrocarbon cyclic group. This divalent aromatic hydrocarbon cyclic group is obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring. Examples of such aromatic hydrocarbon rings include benzene rings and naphthalene rings, with benzene rings being preferred.

[0029] R 1 and R 2 Each independently represents a halogen atom other than a hydrogen atom or a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, or R 1 With R 2 To represent by combining with each other (X represents a single bond or an oxygen atom.) (This indicates the bond with the benzene ring).

[0030] R 3 and R 4 Each can be independently represented by a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms.

[0031] R 5 and R 6 Each can be independently represented by a halogen atom other than a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a phenyl group.

[0032] n1 and n2 are each independent integers from 0 to 2.

[0033] n3 and n4 are each independent integers from 0 to 3.

[0034] n5 and n6 are each independent integers from 0 to 4.

[0035] n7 and n8 are each an independent integer between 0 and 1.

[0036] P 1 P 2 Q 1 Q 2 R 3 R 4 R 5 R 6 and R 7 When each exists in multiple forms, multiple P 1P 2 Q 1 Q 2 R 3 R 4 R 5 R 6 and R 7 They can be the same or different.

[0037] As diamines (d0), compounds represented by the following formulas (d0-1) to (d0-22) can be listed.

[0038] [Chemistry 5]

[0039] As for tetracarboxylic acid dianhydride (t1), there are no particular limitations as long as the above condition (i) is met, but aromatic tetracarboxylic acid dianhydride containing 1 to 5 benzene rings is preferred.

[0040] Specific examples include pyromellitic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2,7,8-tetracarboxylic dianhydride, naphthalene-2,3,5,6-tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, biphenyl-2,2',3,3'-tetracarboxylic dianhydride, biphenyl-2,3,3',4'-tetracarboxylic dianhydride, biphenyl-3,3',4,4'-tetracarboxylic dianhydride, anthracene-1,2,3,4-tetracarboxylic dianhydride, and anthracene-1, 2,5,6-Tetracarboxylic dianhydride, anthracene-1,2,6,7-tetracarboxylic dianhydride, anthracene-1,2,7,8-tetracarboxylic dianhydride, anthracene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,3,4-tetracarboxylic dianhydride, phenanthrene-1,2,5,6-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, phenanthrene-2,3,5,6-tetracarboxylic dianhydride, phenanthrene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-2,3,9,10-tetracarboxylic dianhydride, phenanthrene-3,4,5,6-tetracarboxylic dianhydride, phenanthrene-3,4,9,10-tetracarboxylic dianhydride, etc. These can be used alone or in combination of two or more.

[0041] From the viewpoint of improving the function of the obtained membrane, aromatic tetracarboxylic dianhydrides with one or two benzene rings are preferred. Specifically, one or more aromatic tetracarboxylic dianhydrides represented by any one of formulas (C1) to (C12) are preferred, and one or more aromatic tetracarboxylic dianhydrides represented by any one of formulas (C1) to (C7) and (C9) to (C11) are more preferred.

[0042] [Chemistry 6]

[0043] It should be noted that, as long as it does not adversely affect the obtained resin layer, other tetracarboxylic acid dianhydrides can also be used in combination with the above-mentioned tetracarboxylic acid dianhydride (t1).

[0044] Other specific examples of tetracarboxylic dianhydrides include: 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic dianhydride, and other alicyclic tetracarboxylic dianhydrides.

[0045] In this invention, the amount of tetracarboxylic dianhydride (t1) or its derivative used in conjunction with tetracarboxylic dianhydride (t0) or its derivative is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20, based on the molar ratio of (t0):(t1).

[0046] In this invention, the total amount of tetracarboxylic dianhydride (t0) or its derivatives and tetracarboxylic dianhydride (t1) or its derivatives used in all tetracarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and most preferably 100 mol%.

[0047] By using this dosage, it is possible to obtain a film with excellent reproducibility, exhibiting superior adhesion to the substrate and inorganic insulating film, as well as heat resistance.

[0048] As a diamine (d1), there are no particular limitations as long as the above condition (ii) is met, but it is preferred to be an aromatic diamine containing 1 to 5 benzene rings.

[0049] Specific examples of diamines (d1) include: 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene (m-phenylenediamine), 1,2-diaminobenzene (o-phenylenediamine), 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,6-dimethyl-p-phenylenediamine, 2,4,6-trimethyl-1,3-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, and other diamines with one benzene ring; 1,2-naphthylenediamine, 1,3-naphthylenediamine, 1,4-naphthylenediamine, 1,5-naphthylenediamine, 1,6-naphthylenediamine, 1,7-naphthylenediamine, and 1,8-naphthylenediamine. Diamines with two benzene rings, such as 2,3-naphthyldiamine, 2,6-naphthyldiamine, 4,4'-biphenyldiamine, 3,3'-dimethylbiphenylamine, and 2,2'-dimethylbiphenylamine; and diamines with three benzene rings, such as 1,5-diaminoanthracene, 2,6-diaminoanthracene, 9,10-diaminoanthracene, 1,8-diaminophenanthrene, 2,7-diaminophenanthrene, 3,6-diaminophenanthrene, 9,10-diaminophenanthrene, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 4,4”-diamino-p-terphenyl, and 4,4”-diamino-m-terphenyl, etc., but not limited to these. They can be used alone or in combination of two or more.

[0050] From the viewpoint of improving the function of the obtained membrane, p-phenylenediamine, m-phenylenediamine, 2,2'-dimethylbenzidine, and 4,4”-diamino-p-terphenyl are preferred.

[0051] Furthermore, other diamines can be used in combination with the diamine (d1) as long as they do not adversely affect the resulting resin layer.

[0052] Specific examples of other diamines include 1,4-diaminocyclohexane, 1,4-cyclohexanebis(methylamine), 4,4'-diaminodicyclohexylmethane, bis(4-amino-3-methylcyclohexyl)methane, and 3(4),8(9)-bis(aminomethyl)tricyclic [5.2.1.0]. 2,6 [Decane, 2,5(6)-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,3-diaminoadamantane, 3,3'-diamino-1,1'-diadamantane, 1,6-diaminodadamantane (1,6-aminopentane[7.3.1.1] 4,12 ,0 2,7 .0 6,11 Alicyclic diamines such as tetradecane; aliphatic diamines such as tetramethylenediamine and hexamethylenediamine.

[0053] In this invention, the amount of diamine (d1) used in conjunction with diamine (d0) is preferably 5:95 to 95:5, more preferably 10:90 to 90:10, and even more preferably 20:80 to 80:20, based on the molar ratio of (d0):(d1).

[0054] In this invention, the total amount of diamine (d0) and diamine (d1) in the total diamine composition is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more. By using such amounts, a film with excellent adhesion to the substrate and inorganic insulating film, as well as heat resistance, can be obtained with good reproducibility.

[0055] The ratio of diamine to tetracarboxylic acid is appropriately determined considering factors such as the target molecular weight or molecular weight distribution, the type of diamine, or the type of tetracarboxylic dianhydride or its derivatives. Therefore, it cannot be generalized. When the total molar number of diamine is set to 1.0, the total molar number of tetracarboxylic acid is preferably 0.8 to 1.2. When the total molar number of tetracarboxylic acid is less than 1.0, i.e., less than the molar number of diamine, the polymer ends with an amino structure; when it is greater than 1.0, i.e., greater than the molar number of diamine, the polymer ends with a carboxylic anhydride or dicarboxylic acid structure.

[0056] The organic solvents used in the synthesis of polyamic acids are not particularly limited as long as they do not adversely affect the reaction. Specific examples include: m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-propoxy-N,N-dimethylpropionamide, 3-isopropoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, 3-sec-butoxy-N,N-dimethylpropionamide, and 3-tert-butoxy-N,N-dimethylpropylamide. c -Butyrolactone, etc. It should be noted that one organic solvent can be used alone or in combination of two or more.

[0057] The reaction temperature for the synthesis of polyamic acid can be appropriately set within the melting point to boiling point range of the solvent used, typically around 0℃ to 100℃. From the viewpoint of preventing imidization of the obtained polyamic acid in solution and maintaining a high content of polyamic acid units, it is preferable to be around 0℃ to 70℃, more preferably around 0℃ to 60℃, and even more preferably around 0℃ to 50℃. The reaction time depends on the reaction temperature and the reactivity of the raw materials, and therefore cannot be generalized, typically ranging from 1 hour to 100 hours.

[0058] The weight-average molecular weight of the polyamic acid thus obtained is typically around 5,000 to 500,000. From the viewpoint of improving the function of the obtained membrane, it is preferably around 6,000 to 200,000, and more preferably around 7,000 to 150,000. It should be noted that in this invention, the weight-average molecular weight is a converted value of polystyrene based on gel permeation chromatography (GPC).

[0059] [(B) Imidination promoter] The imidization accelerator, as component (B), is a compound used to promote imidization, preferably a compound containing a basic site (e.g., primary amino group, aliphatic heterocycle (e.g., pyrrolidine skeleton), aromatic heterocycle (e.g., imidazole ring, indole ring), or guanidine group, etc.), or a compound that generates the aforementioned basic site during calcination. More preferably, it is a compound that generates the aforementioned basic site during calcination. Preferred examples include amino acids in which part or all of the basic site is protected by a protecting group, or compounds in which the NH group of a nitrogen-containing aromatic heterocycle is protected by a protecting group. As protecting groups for the basic site of the aforementioned amino acid or nitrogen-containing aromatic heterocycle, urethane-based protecting groups such as tert-butoxycarbonyl or 9-fluorenylmethoxycarbonyl can be cited. Specific examples of the aforementioned amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, and ornithine.

[0060] The molecular weight of the compounds used to promote imidization can be less than 2000, less than 1000, or less than 500.

[0061] If a more preferred specific example is the compound used to promote imidization, then N- α -(9-fluorenylmethoxycarbonyl)-N- t -(tert-butoxycarbonyl)-L-histidine, N- α -(tert-butoxycarbonyl)-N- t -(tert-butoxycarbonyl)-L-histidine, 1-tert-butoxycarbonyl imidazole, etc.

[0062] Relative to 100 parts by weight of the polyimide precursor contained in the composition, the content of the above-mentioned compound for promoting imidization contained in the composition of the present invention is preferably 0.1 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, and even more preferably 0.5 to 10 parts by weight.

[0063] [(C) Silane coupling agent] Silane coupling agents, for example, are added to improve the adhesion between the resin film and the object protected by the resin film (e.g., an inorganic insulating film).

[0064] Examples of silane coupling agents include the following silane compounds.

[0065] Amine silane coupling agents such as 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, and 3-aminopropyldiethoxymethylsilane; Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, vinylmethyldimethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane, p-styryltrimethoxysilane, and other vinyl silane coupling agents; Epoxy silane coupling agents such as 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Methacrylic acid-based silane coupling agents such as 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriethoxysilane; Acrylic silane coupling agents such as 3-acryloyloxypropyltrimethoxysilane; 3-Urea-propyltriethoxysilane and other ureoyl-based silane coupling agents; Sulfide-based silane coupling agents include bis(3-(triethoxysilyl)propyl)disulfide and bis(3-(triethoxysilyl)propyl)tetrasulfide. 3-Mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-octanoylthio-1-propyltriethoxysilane and other mercapto-based silane coupling agents; Isocyanate-based silane coupling agents such as 3-isocyanate propyltriethoxysilane and 3-isocyanate propyltrimethoxysilane, as well as silane coupling agents that utilize thermally departing groups to protect their isocyanate groups; Aldehyde-based silane coupling agents such as triethoxysilylbutyraldehyde; Triethoxysilylpropylmethylcarbamate, (3-triethoxysilylpropyl)-tert-butylcarbamate, and other carbamate-based silane coupling agents.

[0066] The molecular weight of silane coupling agents can be below 2000, below 1000, or below 500.

[0067] In addition, there can be one silane coupling agent or a combination of two or more.

[0068] The content of the silane coupling agent is not particularly limited, but is preferably 0.10 to 30.0 parts by weight relative to 100 parts by weight of the polyimide precursor, more preferably 1.0 to 15.0 parts by weight, and even more preferably 3.0 to 10.0 parts by weight.

[0069] The composition for forming a flexible device substrate of the present invention contains an organic solvent. As the organic solvent, the same organic solvent as the reaction solvent of the above-described reaction can be used. From the viewpoint of good dissolution of the polyimide precursor of the present invention and easy preparation of a composition with high uniformity, it is particularly preferred to contain at least one of the amides shown in the following formula (S1), the amides shown in formula (S2) and the amides shown in formula (S3).

[0070] [Chemistry 7]

[0071] In the above formula, R 30 ~R 35 Alkyl groups, each having 1 to 10 carbon atoms, are independently represented. R 36 It represents an alkyl group having 1 to 10 hydrogen atoms or carbon atoms. b represents an integer of 1 or more, preferably an integer of 1 to 5, and more preferably an integer of 1 to 3.

[0072] Specific examples of alkyl groups having 1 to 10 carbon atoms include the same alkyl groups as those described above.

[0073] Specific examples of the organic solvents shown in formulas (S1) to (S3) above include 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-dimethylbutyramide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, etc., with N-methyl-2-pyrrolidone being preferred. These organic solvents can be used alone or in combination of two or more.

[0074] It should be noted that even solvents that individually do not dissolve the polyimide precursor can be used to prepare the composition, as long as the polyimide precursor does not precipitate. In particular, solvents with low surface tension, such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and isoamyl lactate, can be appropriately mixed. Therefore, it is known that coating uniformity is improved when coating onto a substrate, and these solvents can be suitably used in this invention.

[0075] The flexible device substrate forming composition of the present invention can be prepared using conventional methods. As a preferred example of the preparation method, a reaction solution containing the target polyimide precursor obtained by the method described above is filtered, and the concentration of the resulting filtrate is set to a predetermined concentration using the aforementioned organic solvent. By employing this method, not only can the introduction of impurities that might cause deterioration in the adhesion, heat resistance, etc., of the resin film manufactured from the obtained composition be reduced, but the flexible device substrate forming composition can also be obtained efficiently.

[0076] The concentration of the polyimide precursor in the flexible device substrate forming composition of the present invention is appropriately set considering the thickness of the resin film to be formed, the viscosity of the composition, etc., and is typically about 1% to 30% by mass, preferably about 1% to 20% by mass. By setting such a concentration, a reproducible concentration of 0.05 to 5% can be obtained. m A resin film with a thickness of approximately μm. The concentration of the polyimide precursor can be adjusted by adjusting the amount of diamine and tetracarboxylic dianhydride used as raw materials for the polyimide precursor, and by adjusting the amount of the separated polyimide precursor dissolved in the solvent.

[0077] Furthermore, the viscosity of the composition for forming the flexible device substrate of the present invention is appropriately set taking into account factors such as the thickness of the resin film to be produced, and in particular, it is obtained with good reproducibility at 0.05 to 5. m When the desired thickness is a film of about m, the pressure is usually around 5~10000 mPa·s at 25°C, preferably around 10~5000 mPa·s.

[0078] Here, the viscosity can be measured using a commercially available liquid viscosity meter, for example, following the steps described in JIS K 7117-2, at a composition temperature of 25°C. A conical-plate type (conical plate type) rotational viscometer is preferred, and a similar type is even more preferred, using a 1°34'×R24 standard conical rotor, measured at a composition temperature of 25°C. An example of such a rotational viscometer is the TVE-25L manufactured by Toki Sangyo Co., Ltd.

[0079] It should be noted that the composition for forming flexible device substrates of the present invention may include, for example, a crosslinking agent to improve film strength, in addition to at least one of the polyimide precursor, imidization accelerator and silane coupling agent and an organic solvent.

[0080] The above-described composition for forming a flexible device substrate of the present invention is coated onto a substrate, and the resulting coating is heated to thermally imidize the polyimide precursor, thereby obtaining a resin film with excellent adhesion to the substrate and the inorganic insulating film and heat resistance.

[0081] When forming the resin film of the present invention on a substrate, the resin film can be formed on a portion of the substrate surface or on the entire surface. Methods of forming the resin film on a portion of the substrate surface include forming the resin film only within a defined area of ​​the substrate surface, and forming the resin film on the entire substrate surface in a patterned manner such as a dot pattern or a line and space pattern. It should be noted that, in the present invention, the substrate refers to a substrate on which the flexible device substrate forming composition of the present invention is coated, and refers to a substrate used for manufacturing flexible electronic devices, etc.

[0082] Examples of substrates include glass, plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy resin, melamine, triacetyl cellulose, ABS, AS, norbornene resins, etc.), metals (silicon wafers, etc.), wood, paper, and slate. In this invention, the resin film, in particular, has sufficient adhesion, therefore a glass substrate is preferred. Furthermore, the substrate surface can be composed of a single material or two or more materials. Methods of using two or more materials to form the substrate surface include situations where a portion of the substrate surface is composed of a single material and the remaining portion is composed of other materials, or where a material forming a dotted pattern, line-spaced pattern, or other pattern shape is present within other materials on the entire substrate surface.

[0083] There are no particular limitations on the method of coating the composition for forming the flexible device substrate of the present invention onto the substrate. Examples include casting coating, spin coating, doctor blade coating, dip coating, roll coating, bar coating, mold coating, inkjet coating, and printing methods (letterpress, gravure, lithography, screen printing, etc.).

[0084] The heating temperature for imidization is typically determined appropriately within the range of 50°C to 550°C, preferably exceeding 150°C but below 510°C. Setting the heating temperature in this way prevents the resulting film from becoming brittle and allows the imidization reaction to proceed fully. The heating time varies depending on the heating temperature and therefore cannot be generalized, typically ranging from 5 minutes to 5 hours. Furthermore, the imidization rate should be in the range of 50% to 100%. It should be noted that the imidization rate mentioned in this specification refers to the proportion of imide groups in the total stoichiometry of imide groups and carboxyl groups (or their derivatives) derived from tetracarboxylic dianhydride or its derivatives.

[0085] As a preferred example of the heating method in this invention, a method is to heat at 50°C to 150°C for 5 minutes to 2 hours, then directly and gradually increase the heating temperature, and finally heat at a temperature exceeding 150°C but below 510°C for 30 minutes to 4 hours. Particularly preferred is to heat at 50°C to 150°C for 5 minutes to 2 hours, then heat at a temperature exceeding 150°C but below 350°C for 5 minutes to 2 hours, and finally heat at a temperature exceeding 350°C but below 450°C for 30 minutes to 4 hours.

[0086] Appliances used for heating include, for example, hot plates and ovens. The heating atmosphere can be air or an inert gas, and can be at atmospheric pressure or under reduced pressure.

[0087] The thickness of the resin film is typically 0.01~50 mm. m From a productivity point of view, the optimal value is approximately 0.05 to 20 m. m Approximately m. Furthermore, the desired thickness is achieved by adjusting the thickness of the coating before heating.

[0088] The resin film described above possesses excellent adhesion to the substrate, particularly glass substrates, as well as excellent adhesion to inorganic insulating films, transparency, and heat resistance. Furthermore, these properties remain unchanged before and after heat treatment, especially in TFT processes, demonstrating stable performance. Therefore, the resin film of this invention will not damage the resin substrate of flexible electronic devices during the manufacturing process and functions as a permanent film maintaining transparency after the manufacturing process.

[0089] Hereinafter, an example of a method for manufacturing a flexible electronic device using the resin film of the present invention will be described.

[0090] Using the flexible device substrate forming composition of the present invention, a resin film is formed on a glass substrate by the above method. To ensure insulation, an insulating film is further formed on the resin film. Known methods can be cited as examples, such as reactive sputtering with N2 or O2 gas, and plasma CVD.

[0091] The sputtering conditions for using sputtering are as follows: target is Si, sputtering gas is Ar and N2 or O2, target-substrate distance is 50~200mm, process pressure is 0.1~0.7Pa, RF output power is 200~400W, and sputtering time is 10~30 minutes.

[0092] The thickness of the resulting insulating film is preferably 100 to 1000 nm, and more preferably 250 to 800 nm.

[0093] The insulating film is then subjected to repeated processes such as metal (e.g., Al, Cu) sputtering, photolithographic patterning, chemical evaporation, and annealing to complete the TFT wiring layer. Furthermore, if necessary, the substrate thickness can be adjusted by further etching the glass substrate, thereby improving the flexibility of the electronic device.

[0094] As insulating films, inorganic insulating films such as silicon nitride, silicon dioxide, PSG (Phospho Silicate Glass), and BPSG (Boron Phospho Silicate Glass), as well as organic insulating films such as polyimide resins and organosilicon can be used. These insulating films can be used alone or in combination of two or more.

[0095] Example The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Additionally, the abbreviations for compounds and solvents are as follows.

[0096] (Organic solvent) NMP: N-methyl-2-pyrrolidone GBL: c -Butyrolactone BCS: Butyl Solvent (Diamine) DA-1 to DA-6: Compounds represented by the following structural formulas (DA-1) to (DA-6), respectively. [Chemistry 8]

[0097] Of the diamines mentioned above, DA-1, DA-5, and DA-6 are included in the range of diamines (d0), and DA-2 and DA-3 are included in the range of diamines (d1).

[0098] (Tetracarboxylic acid dianhydride) CA-1~CA-5: Compounds represented by the following structural formulas (CA-1)~(CA-5), respectively. [Chemistry 9]

[0099] Of the aforementioned tetracarboxylic dianhydrides, CA-1 and CA-3 are included in the range of tetracarboxylic dianhydrides (t0), and CA-2 and CA-4 are included in the range of tetracarboxylic dianhydrides (t1).

[0100] (Additives (imideation accelerators)) Add-B1~Add-B3: Compounds represented by the following structural formulas (Add-B1)~(Add-B3) (where Boc represents tert-butoxycarbonyl). [Chemistry 10]

[0101] (Additives (silane coupling agents)) Add-C1: The compound represented by the following structural formula (Add-C1) Add-C2: X-12-1195 (A terminated isocyanate-type silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.) Add-C3: X-12-1293 (A terminated isocyanate-type silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.) Add-C4: X-12-1308ES (A terminated isocyanate-type silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd.) Add-C5~C7: Compounds represented by the following structural formulas (Add-C5)~(Add-C7) [Chemistry 11]

[0102] (In the above formula, Me represents methyl and Et represents ethyl.) <Viscosity Measurement> The measurement was performed using a TVE-22H type E viscometer (manufactured by Toki Sangyo Co., Ltd.), with a sample volume of 1.1 mL and a conical rotor TE-1 (1°34', R24), at a temperature of 25°C.

[0103] <Determination of molecular weight> Using the following room-temperature GPC (gel permeation chromatography) apparatus under the following conditions, calculate Mn (number average molecular weight) and Mw (weight average molecular weight) using polyethylene glycol and polyethylene oxide conversion values.

[0104] GPC unit: GPC-101 (manufactured by Resonac). Chromatographic columns: GPC KD-803 and GPC KD-805 (manufactured by Resonac) in tandem. Column temperature: 50℃ Eluent: N,N-dimethylformamide (as additives, lithium bromide monohydrate (LiBr·H2O) 30 mmol / L, phosphoric acid·anhydrous crystals (o-phosphoric acid) 30 mmol / L, tetrahydrofuran (THF) 10 mL / L). Flow rate: 1.0 mL / min Standard samples used for preparing the standard curve: EasiVial PEG / PEO polyethylene glycol oxide PL2080-0201 (molecular weight: approx. 1500, approx. 4000, approx. 13000, approx. 30000, approx. 70000, approx. 130000, approx. 500000, approx. 1000000, approx. 1500000) (manufactured by GL Sciences). <Synthesis of Diamines> (Synthetic Example 1: Synthesis of DA-5) [Chemistry 12]

[0105] In a 100 mL four-necked flask, 11H-benzo[b]fluorene-11-one (3.91 g, 17.0 mmol), aniline hydrochloride (2.20 g, 17.0 mmol), and aniline (7.9 g) were added, and the mixture was stirred at 150 °C for 24 hours. After the reaction was complete, ethyl acetate (100 g) was added at room temperature, and the mixture was washed three times with pure water (50 g). The organic layer was concentrated and purified by column chromatography using heptane / ethyl acetate (1:1 (v / v)). The resulting solution was concentrated, and crystals precipitated. The crystals were then washed with 2-propanol (20 g) to obtain DA-5 (yield: 5.5 g, 13.8 mmol, 81%).

[0106] 1 H-NMR(DMSO-d6):8.34(1H,s),8.00(1H,d),7.96(1H,d),7.86(1H,d),7.79(1H,s),7.30-7.49(5H,m),6.81(4H,d),6.42(4H,d),4.92(4H,s) (Single Synthesis Example 2: Synthesis of DA-6) DA-6 was synthesized using 2,7-dibromo-9,9'-spirodi[9H-fluorene] as a raw material, according to the synthesis method described in Japanese Patent Application Publication No. 2019-529616.

[0107] 1 H-NMR(DMSO-d6): δ(ppm)=7.95(2H,d),7.33-7.39(4H,m),7.10-7.17(2H,m),6.66(2H,d),6.48(2H,dd),5.77(2H,d),4.83(4H,s) <Polymer Synthesis> (Example 1) DA-1 (25.1 g, 72.0 mmol) and NMP (142 g) were added to a 300 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube. The mixture was stirred at room temperature (25 °C) while nitrogen was being introduced, until dissolved. Then, CA-1 (8.25 g, 18.0 mmol) and NMP (46.8 g) were added, and the mixture was stirred at 40 °C for 1 hour. Subsequently, CA-2 (11.6 g, 53.3 mmol) and NMP (65.6 g) were added, and the mixture was stirred at 40 °C for 16 hours, thereby obtaining a polyamic acid solution (A-1) with a solid content of 15% by mass (viscosity: 704 mPa·s). The Mn of this polyamic acid was 14232, and the Mw was 37167.

[0108] (Examples 2 to 19) By changing the type and amount of the diamine and tetracarboxylic acid components used, but otherwise following the same steps as in Polymerization Example 1, polyamic acid solutions (A-2) to (A-19) with a solid content concentration of 15% by mass were obtained. The amounts of diamine and tetracarboxylic acid components used in the polymerization of polyamic acid, the viscosity of the obtained polymer, and Mn and Mw are shown in Table 1.

[0109] [Table 1]

[0110] <Preparation of Compositions for Forming Flexible Device Substrates> (Preparation Example 1) Polyamic acid solution A-1 (2.13 g) was placed in a 20 mL screw-capped tube, and Add-B1 (0.0160 g) as additive 1 and Add-C1 (0.320 g of 5% NMP solution as additive 2) were added. The mixture was stirred at room temperature (25°C) for 5 hours to obtain a flexible device substrate forming composition (B-1) with a polymer solids concentration of 13% by mass. In another 20 mL screw-capped tube, polyamic acid solution A-1 (2.13 g), Add-B1 (0.0160 g) as additive 1, and Add-C1 (0.320 g of 5% NMP solution as additive 2) were added, and then diluted. The mixture was stirred at room temperature (25°C) for 5 hours to obtain a flexible device substrate forming composition (C-1) with a polymer solids concentration of 4% by mass.

[0111] (Preparation Examples 2 to 37) As shown in Table 2 below, the polyamic acid solution, additives, and solvents used were changed, but the same operation as in Preparation Example 1 was performed to obtain flexible device substrate forming compositions (B-2) to (B-37) with a polymer solids concentration of 13% by mass and flexible device substrate forming compositions (C-2) to (C-37) with a polymer solids concentration of 4% by mass. It should be noted that the additives Add-C1 to Add-C7 in Table 2 were added in the form of a solution containing 5% by mass of NMP.

[0112] [Table 2]

[0113] <Property Evaluation of Polyimide> (Example 1) Using the flexible device substrate forming compositions (B-1) and (C-1) obtained in Preparation Example 1, the transmittance, TGA (thermogravimetric analysis), and silicon nitride film adhesion were evaluated according to the methods described below.

[0114] [Transmittance Evaluation] The flexible device substrate forming composition (C-1) obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG). After being fired on a hot plate at 70°C for 90 seconds, it was fired in an infrared furnace at 230°C under a nitrogen atmosphere for 30 minutes, and then fired in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce an alkali-free glass substrate with a polyimide film thickness of 50 nm. The substrate with the polyimide film was measured using a Shimadzu UV-3600 at a temperature of 25°C and a scanning wavelength of 350–800 nm. An uncoated alkali-free glass substrate was used as a reference. The transmittance at a wavelength of 450 nm was evaluated and found to be 93.2%.

[0115] [TGA Evaluation] The flexible device substrate forming composition (B-1) obtained in Preparation Example 1 was spin-coated onto a 4-inch silicon wafer. After being fired on a hot plate at 70°C for 900 seconds, it was fired in an infrared heating furnace at 230°C under a nitrogen atmosphere for 30 minutes, and then fired in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to form a film with a thickness of 5 mm. m A silicon wafer with a polyimide film. The polyimide film is cut from the silicon wafer using a dicing tool, in a capacity of 100... m 8.0 mg was weighed into an aluminum pan of size L. The aluminum pan containing the sample was placed in the furnace of a thermogravimetric analysis apparatus TGA / DSC3+ (manufactured by Metler Toledo), and the weight loss was measured when the temperature was increased from 25 °C to 550 °C at a rate of 10 °C / min. To eliminate the influence of moisture due to hygroscopicity, the weight at 150 °C was set as 100% of the baseline, and the temperature at which the weight was less than 99.0% was set as Td1 (1% weight loss temperature) for evaluation, with a result of 487 °C.

[0116] [Silicon nitride film adhesion test] The flexible device substrate forming composition (C-1) obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG (registered trademark) manufactured by Corning Corporation). After being fired on a hot plate at 70°C for 90 seconds, it was fired in an infrared furnace at 230°C under a nitrogen atmosphere for 30 minutes, and then fired in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce an alkali-free glass substrate with a polyimide film thickness of 50 nm. The obtained alkali-free glass substrate with a polyimide film was placed in the chamber of an SRS-700T / LL RF sputtering apparatus (manufactured by SANYU Electronics Co., Ltd.) with the polyimide film side facing the Si surface of the target. Furthermore, under the conditions shown below, a silicon nitride film was fabricated on a polyimide film by reactive sputtering with N2 gas (sputtering conditions = target: Si, sputtering gases: Ar and N2, target-substrate distance: 100 mm, process pressure: 0.4 Pa, RF output power: 300 W, sputtering time: 17 minutes, silicon nitride film thickness: 300 nm). The resulting alkali-free glass substrate with the polyimide film and silicon nitride film was further placed in a muffle furnace at 400°C for 30 minutes, then rapidly cooled to room temperature. The separation of the silicon nitride film and the polyimide substrate was evaluated. Observed separation was classified as "poor," and no separation was classified as "good," with the result evaluated as "good." The substrate was then further placed in a muffle furnace at 450°C for 30 minutes, then rapidly cooled to room temperature. The separation of the silicon nitride film and the polyimide substrate due to thermal expansion was evaluated. Observed separation was classified as "poor," and no separation was classified as "good," with the result evaluated as "good."

[0117] In addition, the flexible device substrate forming composition (B-1) obtained in Preparation Example 1 was spin-coated onto a 5 cm square, 0.7 mm thick alkali-free glass substrate (Eagle-XG (registered trademark) manufactured by Corning Corporation). After being fired on a hot plate at 70°C for 900 seconds, it was fired in an infrared heating furnace at 230°C under a nitrogen atmosphere for 30 minutes, and then fired in a clean oven at 400°C under a nitrogen atmosphere for 30 minutes to produce a film with a thickness of 5 mm. m An alkali-free glass substrate with a polyimide film of m thickness was prepared. A silicon nitride film was fabricated by reactive sputtering with N2 gas, following the same procedure as for the alkali-free glass substrate with a polyimide film of 50 nm thickness. The resulting alkali-free glass substrate with the polyimide film and silicon nitride film was further placed in a muffle furnace at 400 °C for 30 minutes, then rapidly cooled to room temperature. The presence of delamination between the silicon nitride film and the polyimide substrate due to thermal expansion was evaluated. Delamination was observed and categorized as "poor," while no delamination was observed and categorized as "good." The overall result was rated as "good."

[0118] (Examples 2 to 29, Comparative Examples 1 to 8) The flexible device substrate forming compositions were changed to (B-2) to (B-37) and (C-2) to (C-37), respectively. Otherwise, the transmittance, TGA (thermogravimetric analysis), and silicon nitride film adhesion were evaluated following the same steps as in Example 1. The evaluation results are shown in Table 3 below.

[0119] [Table 3]

[0120] As shown in Table 3, by using a composition for forming a flexible device substrate containing polyamic acid with one or both of tetracarboxylic dianhydride (t0) and diamine (d0), and tetracarboxylic dianhydride (t1) and diamine (d1), and further containing an imidization accelerator or a silane coupling agent as additives, a polyimide film with high transmittance and high heat resistance, which does not peel off even after annealing at 400°C, can be obtained. Furthermore, it is shown that when both an imidization accelerator and a silane coupling agent are used as additives, silicon nitride film peeling does not occur even after annealing at 450°C, and the adhesion of the silicon nitride film is improved.

[0121] Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2023-210348, filed on December 13, 2023, are incorporated herein as disclosure of the present invention.

Claims

1. A composition for forming a flexible device substrate, characterized in that, It contains component (A), and at least one of component (B) and component (C); (A) Composition: Polyimide precursor having: a structure derived from a tetracarboxylic dianhydride or a derivative thereof having the structure shown in formula (0-t) or (0-d) below and a diamine having the structure shown in formula (0-d) below, and also having: a structure derived from one or both of a tetracarboxylic dianhydride or a derivative thereof satisfying condition (i) below and a diamine satisfying condition (ii) below, and without fluorine atoms; Condition (i): When there are two dicarboxylic anhydride sites in the molecule that are directly bonded to the aromatic rings, and there are multiple aromatic rings bonded to the dicarboxylic anhydride sites, the aromatic rings bonded to the dicarboxylic anhydride sites are bonded to each other by single bonds, or via aromatic ring bonds, or fused together. Condition (ii): When there are two amino groups directly bonded to the aromatic rings in the molecule and multiple aromatic rings bonded to the amino groups are present, the aromatic rings bonded to the amino groups are bonded to each other by single bonds, or via aromatic ring bonds, or fused together. In formulas (0-t) and (0-d), the hydrogen atoms on the benzene ring are replaced by or not replaced by groups selected from halogen atoms, alkyl groups with 1 to 3 carbon atoms, alkoxy groups with 1 to 3 carbon atoms, and phenyl groups with or without substituents. The two benzene rings bonded to the 9 position of fluorene can be bonded to each other by single bonds or ether bonds. The benzene rings of the fluorene skeleton are replaced by or not replaced by naphthalene rings. The dashed line in formula (0-t) represents the bond with the anhydride site, and the dashed line in formula (0-d) represents the bond with the group having the anhydride site in tetracarboxylic dianhydride, and the bond with the group having the amino group in diamine. (B) Ingredient: Imidization accelerator; (C) Component: Silane coupling agent.

2. The composition for forming a flexible device substrate according to claim 1, wherein, The composition for forming a flexible device substrate contains component (B) and component (C).

3. A flexible electronic device, characterized in that, A resin film is obtained from the composition for forming a flexible device substrate as described in claim 1 or 2.

4. A flexible electronic device, characterized in that, The resin film obtained by the composition for forming a flexible device substrate according to claim 1 or 2 has a glass substrate on one side and an insulating film on the other side.

5. The composition for forming a flexible device substrate according to claim 1 or 2, wherein, The (B) component is a compound having a basic site, a compound having an aromatic heterocycle, or a compound that generates the basic site during firing.

6. The composition for forming a flexible device substrate according to claim 1 or 2, wherein, The content of component (B) is 0.1 to 30 parts by weight relative to 100 parts by weight of the polyimide precursor.

7. The composition for forming a flexible device substrate according to claim 1 or 2, wherein, The component (C) is an amine-based silane coupling agent, a vinyl-based silane coupling agent, an epoxy-based silane coupling agent, a methacrylic acid-based silane coupling agent, an acrylic acid-based silane coupling agent, a urea-based silane coupling agent, a sulfide-based silane coupling agent, a mercapto-based silane coupling agent, an isocyanate-based silane coupling agent, and a silane coupling agent that uses a thermally departing group to protect its isocyanate group, an aldehyde-based silane coupling agent, or a carbamate-based silane coupling agent.

8. The composition for forming a flexible device substrate according to claim 1 or 2, wherein, The content of component (C) is 0.10 parts by weight to 30.0 parts by weight relative to 100 parts by weight of the polyimide precursor.

9. The composition for forming a flexible device substrate according to claim 1 or 2, wherein, The composition for forming the flexible device substrate also includes an organic solvent.

10. The flexible electronic device according to claim 3, wherein, The thickness of the resin film is 0.

05. μ m~20 μ m.

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